Study of Endocrine Factors Influencing Mammary Development and Secretion in the Mouse

Abstract

At sexual maturity the mammary gland of the female mouse consists of the primary duct (galactophore) system. Theelin injections or ovarian implants induce a similar galactophore development in both castrate males and females. No response of the mature female gland is noted after theelin treatment. This is in agreement with the findings of Turner et al., 1 that theelin, theelol or crude estrogenic extracts will not influence the mammae beyond the development of the galactophores. Thus the follicular hormone seems responsible for the establishment of the primary duct system.

It is more or less generally believed that the corpus luteum governs the advanced development of the mammary gland. A satisfactory luteal extract was not obtained. However, luteinization of the ovaries by extracts of the anterior lobe pituitary 20 or of pregnancy urinet induces development of the secondary ducts (interlobular canals) and later of the alveolar anlagen. In the intact animal this development is much more rapid after pituitary administration than after Antuitrin S. After ovariectomy, neither of these substances will bring about growth of the interlobular canals. Total hysterectomy also inhibits their development even though functional corpora lutea are present in the ovaries. If hysterectomy is done before the appearance of any interlobular canals, they do not appear even after extended periods of luteinizing treatment. Interlobular canals only partially developed at the time of hysterectomy are inhibited from any further growth. Thus it appears that the formation of these secondary ducts is dependent upon the uterus, the activity of which is in turn governed by the corpus luteum.

In the normally developing mammae the alveolar anlagen appear after the interlobular canal system is well established, forming as dense nodular masses which balloon out into grape-cluster lobules when they pass into the secretory phase.